The photo below shows a typical queen excluder that is used in the hive. This grill-like plastic panel has gaps in it to keep the larger bodied queen from entering the honey supers. This stops her laying eggs throughout the honey cells and spoiling the mix, so to speak. It also means it hinders the natural flow of the bees to venture up into the honey supers and place the nectar where it should go. This coming year we hope to do away with the excluders and leave plenty of brood space in the lower hive by adding additional brood boxes. Which really means we are trying something new that may give us more honey!
I came across this graph recently from a wonderful site dedicated to beekeeping. I had no idea a bee could sting in so many varied body parts. They are out West so the info is not quite relative to ours but the information is extensive. Have a look whenever you have the chance. Many thanks to them for supplying so much information. http://strathconabeekeepers.blogspot.ca